﻿<!DOCTYPE html>
<html>
<head>
  <title>Pipes</title>
  <!-- Copyright 1998-2020 by Northwoods Software Corporation. -->
  <meta name="description" content="An editor for snapping pipes together and moving and rotating them as a single assembly." />
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script id="code">
    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
      var $ = go.GraphObject.make;  // for more concise visual tree definitions

      myDiagram =
        $(go.Diagram, "myDiagramDiv",
          {
            initialScale: 1.5,
            "commandHandler.defaultScale": 1.5,
            allowLink: false,  // no user-drawn links
            // use a custom DraggingTool instead of the standard one, defined below
            draggingTool: new SnappingTool(),
            contextMenu:
              $("ContextMenu",
                makeButton("Paste",
                  function(e, obj) { e.diagram.commandHandler.pasteSelection(e.diagram.toolManager.contextMenuTool.mouseDownPoint); },
                  function(o) { return o.diagram.commandHandler.canPasteSelection(o.diagram.toolManager.contextMenuTool.mouseDownPoint); }),
                makeButton("Undo",
                  function(e, obj) { e.diagram.commandHandler.undo(); },
                  function(o) { return o.diagram.commandHandler.canUndo(); }),
                makeButton("Redo",
                  function(e, obj) { e.diagram.commandHandler.redo(); },
                  function(o) { return o.diagram.commandHandler.canRedo(); })
              ),
            "undoManager.isEnabled": true
          });

      // To simplify this code we define a function for creating a context menu button:
      function makeButton(text, action, visiblePredicate) {
        return $("ContextMenuButton",
          $(go.TextBlock, text),
          { click: action },
          // don't bother with binding GraphObject.visible if there's no predicate
          visiblePredicate ? new go.Binding("visible", "", function(o, e) { return o.diagram ? visiblePredicate(o, e) : false; }).ofObject() : {});
      }

      // when the document is modified, add a "*" to the title and enable the "Save" button
      myDiagram.addDiagramListener("Modified", function(e) {
        var button = document.getElementById("SaveButton");
        if (button) button.disabled = !myDiagram.isModified;
        var idx = document.title.indexOf("*");
        if (myDiagram.isModified) {
          if (idx < 0) document.title += "*";
        } else {
          if (idx >= 0) document.title = document.title.substr(0, idx);
        }
      });

      myDiagram.nodeTemplateMap.add("Comment",
        $(go.Node,
          new go.Binding("location", "loc", go.Point.parse).makeTwoWay(go.Point.stringify),
          $(go.TextBlock,
            { stroke: "brown", font: "9pt sans-serif" },
            new go.Binding("text"))
        ));

      // Define the generic "pipe" Node.
      // The Shape gets it Geometry from a geometry path string in the bound data.
      // This node also gets all of its ports from an array of port data in the bound data.
      myDiagram.nodeTemplate =
        $(go.Node, "Spot",
          {
            locationObjectName: "SHAPE",
            locationSpot: go.Spot.Center,
            selectionAdorned: false,  // use a Binding on the Shape.stroke to show selection
            itemTemplate:
              // each port is an "X" shape whose alignment spot and port ID are given by the item data
              $(go.Panel,
                new go.Binding("portId", "id"),
                new go.Binding("alignment", "spot", go.Spot.parse),
                $(go.Shape, "XLine",
                  { width: 6, height: 6, background: "transparent", fill: null, stroke: "gray" },
                  new go.Binding("figure", "id", portFigure),  // portFigure converter is defined below
                  new go.Binding("angle", "angle"))
              ),
            // hide a port when it is connected
            linkConnected: function(node, link, port) {
              if (link.category === "") port.visible = false;
            },
            linkDisconnected: function(node, link, port) {
              if (link.category === "") port.visible = true;
            }
          },
          // this creates the variable number of ports for this Spot Panel, based on the data
          new go.Binding("itemArray", "ports"),
          // remember the location of this Node
          new go.Binding("location", "loc", go.Point.parse).makeTwoWay(go.Point.stringify),
          // remember the angle of this Node
          new go.Binding("angle", "angle").makeTwoWay(),
          // move a selected part into the Foreground layer, so it isn't obscured by any non-selected parts
          new go.Binding("layerName", "isSelected", function(s) { return s ? "Foreground" : ""; }).ofObject(),
          $(go.Shape,
            {
              name: "SHAPE",
              // the following are default values;
              // actual values may come from the node data object via data binding
              geometryString: "F1 M0 0 L20 0 20 20 0 20 z",
              fill: "rgba(128, 128, 128, 0.5)"
            },
            // this determines the actual shape of the Shape
            new go.Binding("geometryString", "geo"),
            // selection causes the stroke to be blue instead of black
            new go.Binding("stroke", "isSelected", function(s) { return s ? "dodgerblue" : "black"; }).ofObject())
        );

      // Show different kinds of port fittings by using different shapes in this Binding converter
      function portFigure(pid) {
        if (pid === null || pid === "") return "XLine";
        if (pid[0] === 'F') return "CircleLine";
        if (pid[0] === 'M') return "PlusLine";
        return "XLine";  // including when the first character is 'U'
      }

      myDiagram.nodeTemplate.contextMenu =
        $("ContextMenu",
          makeButton("Rotate +45",
            function(e, obj) { rotate(obj.part.adornedPart, 45); }),
          makeButton("Rotate -45",
            function(e, obj) { rotate(obj.part.adornedPart, -45); }),
          makeButton("Rotate 180",
            function(e, obj) { rotate(obj.part.adornedPart, 180); }),
          makeButton("Detach",
            function(e, obj) { detachSelection(); }),
          makeButton("Cut",
            function(e, obj) { e.diagram.commandHandler.cutSelection(); },
            function(o) { return o.diagram.commandHandler.canCutSelection(); }),
          makeButton("Copy",
            function(e, obj) { e.diagram.commandHandler.copySelection(); },
            function(o) { return o.diagram.commandHandler.canCopySelection(); }),
          makeButton("Paste",
            function(e, obj) { e.diagram.commandHandler.pasteSelection(e.diagram.toolManager.contextMenuTool.mouseDownPoint); },
            function(o) { return o.diagram.commandHandler.canPasteSelection(o.diagram.toolManager.contextMenuTool.mouseDownPoint); }),
          makeButton("Delete",
            function(e, obj) { e.diagram.commandHandler.deleteSelection(); },
            function(o) { return o.diagram.commandHandler.canDeleteSelection(); }),
          makeButton("Undo",
            function(e, obj) { e.diagram.commandHandler.undo(); },
            function(o) { return o.diagram.commandHandler.canUndo(); }),
          makeButton("Redo",
            function(e, obj) { e.diagram.commandHandler.redo(); },
            function(o) { return o.diagram.commandHandler.canRedo(); })
        );

      // Change the angle of the parts connected with the given node
      function rotate(node, angle) {
        var tool = myDiagram.toolManager.draggingTool;  // should be a SnappingTool
        myDiagram.startTransaction("rotate " + angle.toString());
        var sel = new go.Set(/*go.Node*/);
        sel.add(node);
        var coll = tool.computeEffectiveCollection(sel).toKeySet();
        var bounds = myDiagram.computePartsBounds(coll);
        var center = bounds.center;
        coll.each(function(n) {
          n.angle += angle;
          n.location = n.location.copy().subtract(center).rotate(angle).add(center);
        });
        myDiagram.commitTransaction("rotate " + angle.toString());
      }

      function detachSelection() {
        myDiagram.startTransaction("detach");
        var coll = new go.Set(/*go.Link*/);
        myDiagram.selection.each(function(node) {
          if (!(node instanceof go.Node)) return;
          node.linksConnected.each(function(link) {
            if (link.category !== "") return;  // ignore comments
            // ignore links to other selected nodes
            if (link.getOtherNode(node).isSelected) return;
            // disconnect this link
            coll.add(link);
          });
        });
        myDiagram.removeParts(coll, false);
        myDiagram.commitTransaction("detach");
      }

      // no visual representation of any link data
      myDiagram.linkTemplate = $(go.Link, { visible: false });

      // support optional links from comment nodes to pipe nodes
      myDiagram.linkTemplateMap.add("Comment",
        $(go.Link,
          { curve: go.Link.Bezier },
          $(go.Shape, { stroke: "brown", strokeWidth: 2 }),
          $(go.Shape, { toArrow: "OpenTriangle", stroke: "brown" })
        ));

      // this model needs to know about particular ports
      myDiagram.model =
        $(go.GraphLinksModel,
          {
            copiesArrays: true,
            copiesArrayObjects: true,
            linkFromPortIdProperty: "fid",
            linkToPortIdProperty: "tid"
          });

      // Make sure the pipes are ordered by their key in the palette inventory
      function keyCompare(a, b) {
        var at = a.data.key;
        var bt = b.data.key;
        if (at < bt) return -1;
        if (at > bt) return 1;
        return 0;
      }

      myPalette =
        $(go.Palette, "myPaletteDiv",
          {
            initialScale: 1.2,
            contentAlignment: go.Spot.Center,
            nodeTemplate: myDiagram.nodeTemplate,  // shared with the main Diagram
            "contextMenuTool.isEnabled": false,
            layout: $(go.GridLayout,
              {
                cellSize: new go.Size(1, 1), spacing: new go.Size(5, 5),
                wrappingColumn: 12, comparer: keyCompare
              }),
            // initialize the Palette with a few "pipe" nodes
            model: $(go.GraphLinksModel,
              {
                copiesArrays: true,
                copiesArrayObjects: true,
                linkFromPortIdProperty: "fid",
                linkToPortIdProperty: "tid",
                nodeDataArray: [
                  // Several different kinds of pipe objects, some already rotated for convenience.
                  // Each "glue point" is implemented by a port.
                  // The port's identifier's first letter must be the type of connector or "fitting".
                  // The port's identifier's second letter must be indicate the direction in which a
                  // connection may be made: 0-7, indicating multiples of 45-degree angles starting at zero.
                  // If you want more than one port of a particular type in the same direction,
                  // you will need to add a suffix to the port identifier.
                  // The Spot determines the approximate location of the port on the shape.
                  // The exact position is offset in order to account for the thickness of the stroke.
                  // Each should be shifted towards the center of the shape by the fraction of its
                  // distance from the center times the stroke thickness.
                  // The following offsets assume the strokeWidth == 1.
                  {
                    key: 1,
                    geo: "F1 M0 0 L20 0 20 20 0 20z",
                    ports: [
                      { id: "U6", spot: "0.5 0 0 0.5" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 3, angle: 90,
                    geo: "F1 M0 0 L20 0 20 20 0 20z",
                    ports: [
                      { id: "U6", spot: "0.5 0 0 0.5" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 5,
                    geo: "F1 M0 0 L20 0 20 60 0 60z",
                    ports: [
                      { id: "U6", spot: "0.5 0 0 0.5" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 7, angle: 90,
                    geo: "F1 M0 0 L20 0 20 60 0 60z",
                    ports: [
                      { id: "U6", spot: "0.5 0 0 0.5" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 11,
                    geo: "F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U2", spot: "0.25 1 0.25 -0.5" }
                    ]
                  },
                  {
                    key: 12, angle: 90,
                    geo: "F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U2", spot: "0.25 1 0.25 -0.5" }
                    ]
                  },
                  {
                    key: 13, angle: 180,
                    geo: "F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U2", spot: "0.25 1 0.25 -0.5" }
                    ]
                  },
                  {
                    key: 14, angle: 270,
                    geo: "F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U2", spot: "0.25 1 0.25 -0.5" }
                    ]
                  },
                  {
                    key: 21,
                    geo: "F1 M0 0 L60 0 60 20 50 20 Q40 20 40 30 L40 40 20 40 20 30 Q20 20 10 20 L0 20z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U4", spot: "0 0.25 0.5 0.25" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 22, angle: 90,
                    geo: "F1 M0 0 L60 0 60 20 50 20 Q40 20 40 30 L40 40 20 40 20 30 Q20 20 10 20 L0 20z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U4", spot: "0 0.25 0.5 0.25" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 23, angle: 180,
                    geo: "F1 M0 0 L60 0 60 20 50 20 Q40 20 40 30 L40 40 20 40 20 30 Q20 20 10 20 L0 20z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U4", spot: "0 0.25 0.5 0.25" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 24, angle: 270,
                    geo: "F1 M0 0 L60 0 60 20 50 20 Q40 20 40 30 L40 40 20 40 20 30 Q20 20 10 20 L0 20z",
                    ports: [
                      { id: "U0", spot: "1 0.25 -0.5 0.25" },
                      { id: "U4", spot: "0 0.25 0.5 0.25" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 31,
                    geo: "F1 M0 0 L20 0 20 10 Q20 14.142 22.929 17.071 L30 24.142 15.858 38.284 8.787 31.213 Q0 22.426 0 10z",
                    ports: [
                      { id: "U6", spot: "0 0 10.5 0.5" },
                      { id: "U1", spot: "1 1 -7.571 -7.571", angle: 45 }
                    ]
                  },
                  {
                    key: 32, angle: 90,
                    geo: "F1 M0 0 L20 0 20 10 Q20 14.142 22.929 17.071 L30 24.142 15.858 38.284 8.787 31.213 Q0 22.426 0 10z",
                    ports: [
                      { id: "U6", spot: "0 0 10.5 0.5" },
                      { id: "U1", spot: "1 1 -7.571 -7.571", angle: 45 }
                    ]
                  },
                  {
                    key: 33, angle: 180,
                    geo: "F1 M0 0 L20 0 20 10 Q20 14.142 22.929 17.071 L30 24.142 15.858 38.284 8.787 31.213 Q0 22.426 0 10z",
                    ports: [
                      { id: "U6", spot: "0 0 10.5 0.5" },
                      { id: "U1", spot: "1 1 -7.571 -7.571", angle: 45 }
                    ]
                  },
                  {
                    key: 34, angle: 270,
                    geo: "F1 M0 0 L20 0 20 10 Q20 14.142 22.929 17.071 L30 24.142 15.858 38.284 8.787 31.213 Q0 22.426 0 10z",
                    ports: [
                      { id: "U6", spot: "0 0 10.5 0.5" },
                      { id: "U1", spot: "1 1 -7.571 -7.571", angle: 45 }
                    ]
                  },
                  {
                    key: 41,
                    geo: "F1 M14.142 0 L28.284 14.142 14.142 28.284 0 14.142z",
                    ports: [
                      { id: "U1", spot: "1 1 -7.321 -7.321" },
                      { id: "U3", spot: "0 1 7.321 -7.321" },
                      { id: "U5", spot: "0 0 7.321 7.321" },
                      { id: "U7", spot: "1 0 -7.321 7.321" }
                    ]
                  },

                  // Example M-F connector pipes
                  /*
                  {
                    key: 107, //angle: 90,
                    geo: "F1 M0 0 L5 0, 5 10, 15 10, 15 0, 20 0, 20 40, 0 40z",
                    ports: [
                      { id: "F6", spot: "0.5 0 0 10.5" },
                      { id: "U2", spot: "0.5 1 0 -0.5" }
                    ]
                  },
                  {
                    key: 108, //angle: 90,
                    geo: "F1 M0 0, 20 0, 20 30, 15 30, 15 40, 5 40, 5 30, 0 30z",
                    ports: [
                      { id: "U6", spot: "0.5 0 0 10.5" },
                      { id: "M2", spot: "0.5 1 0 -0.5" }
                    ]
                  }
                  */

                ]  // end nodeDataArray
              })  // end model
          });  // end Palette

      load();
    } // end init


    // Define a custom DraggingTool
    function SnappingTool() {
      go.DraggingTool.call(this);
    }
    go.Diagram.inherit(SnappingTool, go.DraggingTool);

    // This predicate checks to see if the ports can snap together.
    // The first letter of the port id should be "U", "F", or "M" to indicate which kinds of port may connect.
    // The second letter of the port id should be a digit to indicate which direction it may connect.
    // The ports also need to not already have any link connections and need to face opposite directions.
    SnappingTool.prototype.compatiblePorts = function(p1, p2) {
      // already connected?
      var part1 = p1.part;
      var id1 = p1.portId;
      if (id1 === null || id1 === "") return false;
      if (part1.findLinksConnected(id1).filter(function(l) { return l.category === ""; }).count > 0) return false;
      var part2 = p2.part;
      var id2 = p2.portId;
      if (id2 === null || id2 === "") return false;
      if (part2.findLinksConnected(id2).filter(function(l) { return l.category === ""; }).count > 0) return false;
      // compatible fittings?
      if ((id1[0] === 'U' && id2[0] === 'U') ||
        (id1[0] === 'F' && id2[0] === 'M') ||
        (id1[0] === 'M' && id2[0] === 'F')) {
        // find their effective sides, after rotation
        var a1 = this.effectiveAngle(id1, part1.angle);
        var a2 = this.effectiveAngle(id2, part2.angle);
        // are they in opposite directions?
        if (a1 - a2 === 180 || a1 - a2 === -180) return true;
      }
      return false;
    };

    // At what angle can a port connect, adjusting for the node's rotation
    SnappingTool.prototype.effectiveAngle = function(id, angle) {
      var dir = id[1];
      var a = 0;
      if (dir === '1') a = 45;
      else if (dir === '2') a = 90;
      else if (dir === '3') a = 135;
      else if (dir === '4') a = 180;
      else if (dir === '5') a = 225;
      else if (dir === '6') a = 270;
      else if (dir === '7') a = 315;
      a += angle;
      if (a < 0) a += 360;
      else if (a >= 360) a -= 360;
      return a;
    };

    // Override this method to find the offset such that a moving port can
    // be snapped to be coincident with a compatible stationary port,
    // then move all of the parts by that offset.
    SnappingTool.prototype.moveParts = function(parts, offset, check) {
      // when moving an actually copied collection of Parts, use the offset that was calculated during the drag
      if (this._snapOffset && this.isActive && this.diagram.lastInput.up && parts === this.copiedParts) {
        go.DraggingTool.prototype.moveParts.call(this, parts, this._snapOffset, check);
        this._snapOffset = undefined;
        return;
      }

      var commonOffset = offset;

      // find out if any snapping is desired for any Node being dragged
      var sit = parts.iterator;
      while (sit.next()) {
        var node = sit.key;
        if (!(node instanceof go.Node)) continue;
        var info = sit.value;
        var newloc = info.point.copy().add(offset);

        // now calculate snap point for this Node
        var snapoffset = newloc.copy().subtract(node.location);
        var nearbyports = null;
        var closestDistance = 20 * 20;  // don't bother taking sqrt
        var closestPort = null;
        var closestPortPt = null;
        var nodePort = null;
        var mit = node.ports;
        while (mit.next()) {
          var port = mit.value;
          if (node.findLinksConnected(port.portId).filter(function(l) { return l.category === ""; }).count > 0) continue;
          var portPt = port.getDocumentPoint(go.Spot.Center);
          portPt.add(snapoffset);  // where it would be without snapping

          if (nearbyports === null) {
            // this collects the Nodes that intersect with the NODE's bounds,
            // excluding nodes that are being dragged (i.e. in the PARTS collection)
            var nearbyparts = this.diagram.findObjectsIn(node.actualBounds,
              function(x) { return x.part; },
              function(p) { return !parts.has(p); },
              true);

            // gather a collection of GraphObjects that are stationary "ports" for this NODE
            nearbyports = new go.Set(/*go.GraphObject*/);
            nearbyparts.each(function(n) {
              if (n instanceof go.Node) {
                nearbyports.addAll(n.ports);
              }
            });
          }

          var pit = nearbyports.iterator;
          while (pit.next()) {
            var p = pit.value;
            if (!this.compatiblePorts(port, p)) continue;
            var ppt = p.getDocumentPoint(go.Spot.Center);
            var d = ppt.distanceSquaredPoint(portPt);
            if (d < closestDistance) {
              closestDistance = d;
              closestPort = p;
              closestPortPt = ppt;
              nodePort = port;
            }
          }
        }

        // found something to snap to!
        if (closestPort !== null) {
          // move the node so that the compatible ports coincide
          var noderelpt = nodePort.getDocumentPoint(go.Spot.Center).subtract(node.location);
          var snappt = closestPortPt.copy().subtract(noderelpt);
          // save the offset, to ensure everything moves together
          commonOffset = snappt.subtract(newloc).add(offset);
          // ignore any node.dragComputation function
          // ignore any node.minLocation and node.maxLocation
          break;
        }
      }

      // now do the standard movement with the single (perhaps snapped) offset
      this._snapOffset = commonOffset.copy();  // remember for mouse-up when copying
      go.DraggingTool.prototype.moveParts.call(this, parts, commonOffset, check);
    };

    // Establish links between snapped ports,
    // and remove obsolete links because their ports are no longer coincident.
    SnappingTool.prototype.doDropOnto = function(pt, obj) {
      go.DraggingTool.prototype.doDropOnto.call(this, pt, obj);
      var tool = this;
      // Need to iterate over all of the dropped nodes to see which ports happen to be snapped to stationary ports
      var coll = this.copiedParts || this.draggedParts;
      var it = coll.iterator;
      while (it.next()) {
        var node = it.key;
        if (!(node instanceof go.Node)) continue;
        // connect all snapped ports of this NODE (yes, there might be more than one) with links
        var pit = node.ports;
        while (pit.next()) {
          var port = pit.value;
          // maybe add a link -- see if the port is at another port that is compatible
          var portPt = port.getDocumentPoint(go.Spot.Center);
          if (!portPt.isReal()) continue;
          var nearbyports =
            this.diagram.findObjectsAt(portPt,
              function(x) {  // some GraphObject at portPt
                var o = x;
                // walk up the chain of panels
                while (o !== null && o.portId === null) o = o.panel;
                return o;
              },
              function(p) {  // a "port" Panel
                // the parent Node must not be in the dragged collection, and
                // this port P must be compatible with the NODE's PORT
                if (coll.has(p.part)) return false;
                var ppt = p.getDocumentPoint(go.Spot.Center);
                if (portPt.distanceSquaredPoint(ppt) >= 0.25) return false;
                return tool.compatiblePorts(port, p);
              });
          // did we find a compatible port?
          var np = nearbyports.first();
          if (np !== null) {
            // connect the NODE's PORT with the other port found at the same point
            this.diagram.toolManager.linkingTool.insertLink(node, port, np.part, np);
          }
        }
      }
    };

    // Just move selected nodes when SHIFT moving, causing nodes to be unsnapped.
    // When SHIFTing, must disconnect all links that connect with nodes not being dragged.
    // Without SHIFT, move all nodes that are snapped to selected nodes, even indirectly.
    SnappingTool.prototype.computeEffectiveCollection = function(parts) {
      if (this.diagram.lastInput.shift) {
        var links = new go.Set(/*go.Link*/);
        var coll = go.DraggingTool.prototype.computeEffectiveCollection.call(this, parts);
        coll.iteratorKeys.each(function(node) {
          // disconnect all links of this node that connect with stationary node
          if (!(node instanceof go.Node)) return;
          node.findLinksConnected().each(function(link) {
            if (link.category !== "") return;
            // see if this link connects with a node that is being dragged
            var othernode = link.getOtherNode(node);
            if (othernode !== null && !coll.has(othernode)) {
              links.add(link);  // remember for later deletion
            }
          });
        });
        // outside of nested loops we can actually delete the links
        links.each(function(l) { l.diagram.remove(l); });
        return coll;
      } else {
        var map = new go.Map(/*go.Part, Object*/);
        if (parts === null) return map;
        var tool = this;
        parts.iterator.each(function(n) {
          tool.gatherConnecteds(map, n);
        });
        return map;
      }
    };

    // Find other attached nodes.
    SnappingTool.prototype.gatherConnecteds = function(map, node) {
      if (!(node instanceof go.Node)) return;
      if (map.has(node)) return;
      // record the original Node location, for relative positioning and for cancellation
      map.add(node, new go.DraggingInfo(node.location));
      // now recursively collect all connected Nodes and the Links to them
      var tool = this;
      node.findLinksConnected().each(function(link) {
        if (link.category !== "") return;  // ignore comment links
        map.add(link, new go.DraggingInfo());
        tool.gatherConnecteds(map, link.getOtherNode(node));
      });
    };
    // end SnappingTool class

    function save() {
      document.getElementById("mySavedModel").value = myDiagram.model.toJson();
      myDiagram.isModified = false;
    }
    function load() {
      myDiagram.model = go.Model.fromJson(document.getElementById("mySavedModel").value);
    }
  </script>

</head>
<body onload="init()">
<div id="sample">
  <div id="myPaletteDiv" style="border: solid 1px black; width: 100%; height: 160px"></div>
  <div id="myDiagramDiv" style="border: solid 1px black; width: 100%; height: 500px; margin-top: 3px"></div>
  <p>
    Nodes in this sample use <a>Shape.geometryString</a> to determine their shape.
    You can see more custom geometry examples and read about geometryString
    on the <a href="../intro/geometry.html">Geometry Path Strings Introduction page.</a>
  </p>
  <p>
    As a part's unconnected port (shown by an X) comes close to a stationary port
    with which it is compatible, the dragged selection snaps so that those ports coincide.
    A custom <a>DraggingTool</a>, called <b>SnappingTool</b>, is used to check compatibility.
  </p>
  <p>
    Dragging automatically drags all connected parts.
    Hold down the Shift key before dragging in order to detach a part from the parts it is connected with.
    These functionalities are also controlled by the custom SnappingTool.
  </p>
  <p>
    Use the <a>GraphObject.contextMenu</a> to rotate, detach, or delete a node.
    If it is connected with other parts, the whole collection rotates.
  </p>
  <div>
    <div>
      <button id="SaveButton" onclick="save()">Save</button>
      <button onclick="load()">Load</button>
      Diagram Model saved in JSON format:
    </div>
    <textarea id="mySavedModel" style="width:100%;height:300px">
{ "class": "go.GraphLinksModel",
  "copiesArrays": true,
  "copiesArrayObjects": true,
  "linkFromPortIdProperty": "fid",
  "linkToPortIdProperty": "tid",
  "nodeDataArray": [
{"key":0, "category":"Comment", "text":"Use Shift to disconnect a shape", "loc":"0 -13"},
{"key":1, "category":"Comment", "text":"The Context Menu has more commands", "loc":"0 20"},
{"key":2, "category":"Comment", "text":"Gray Xs are unconnected ports", "loc":"0 -47"},
{"key":3, "category":"Comment", "text":"Dragged shapes snap to unconnected ports", "loc":"0 -80"},
{"key":11, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-187.33333333333331 -69.33333333333331", "angle":0},
{"key":12, "angle":90, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-147.33333333333331 -69.33333333333331"},
{"key":21, "geo":"F1 M0 0 L60 0 60 20 50 20 Q40 20 40 30 L40 40 20 40 20 30 Q20 20 10 20 L0 20z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U4", "spot":"0 0.25 0.5 0.25"},{"id":"U2", "spot":"0.5 1 0 -0.5"} ], "loc":"-137.33333333333331 -9.333333333333314", "angle":0},
{"key":5, "geo":"F1 M0 0 L20 0 20 60 0 60z", "ports":[ {"id":"U6", "spot":"0.5 0 0 0.5"},{"id":"U2", "spot":"0.5 1 0 -0.5"} ], "loc":"-197.33333333333331 -19.333333333333314", "angle":0},
{"key":13, "angle":180, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-147.33333333333331 30.666666666666685"},
{"key":14, "angle":270, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-187.33333333333331 30.666666666666685"},
{"key":-7, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-76.66666666666663 -8.666666666666657", "angle":0},
{"key":-8, "angle":90, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-36.66666666666663 -8.666666666666657"},
{"key":-9, "angle":180, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-36.66666666666663 31.333333333333343"},
{"key":-10, "angle":270, "geo":"F1 M0 40 L0 30 Q0 0 30 0 L40 0 40 20 30 20 Q20 20 20 30 L20 40z", "ports":[ {"id":"U0", "spot":"1 0.25 -0.5 0.25"},{"id":"U2", "spot":"0.25 1 0.25 -0.5"} ], "loc":"-76.66666666666663 31.333333333333343"}
],
  "linkDataArray": [
{"from":12, "to":11, "fid":"U2", "tid":"U0"},
{"from":5, "to":11, "fid":"U6", "tid":"U2"},
{"from":13, "to":21, "fid":"U2", "tid":"U2"},
{"from":14, "to":5, "fid":"U0", "tid":"U2"},
{"from":13, "to":14, "fid":"U0", "tid":"U2"},
{"from":-8, "to":-7, "fid":"U2", "tid":"U0"},
{"from":-9, "to":-8, "fid":"U2", "tid":"U0"},
{"from":-10, "to":-7, "fid":"U0", "tid":"U2"},
{"from":-10, "to":-9, "fid":"U2", "tid":"U0"}
]}
    </textarea>
  </div>
</div>
</body>
</html>
